Cell Division and Chromosomes Flashcards
Cell cycle
the period of time between one cell division and the next; consists of interphase, mitosis, and cytokinesis
Mitosis
cell division that results in identical cells; used for the growth and repair of organisms
Meiosis
cell division that results in cells that have half the normal chromosome number (haploid gametes); also called reduction division
Chromosome
a thick, rod-shaped body in the nucleus that forms when chromatin (long, stringy DNA) supercoils around the balls of histone proteins in prophase of mitosis and meiosis
Genetic material
DNA; contains the genes that direct the synthesis of proteins needed by the cell; exists as chromatin or chromosomes
Cell division
the period of the cell cycle where the cell is actively dividing; composed of mitosis and cytokinesis stages
Karyotype
pictorial representation of all the chromosomes of a cell arranged in homologous pairs according to size, centromere position, and banding pattern; used to diagnose abnormalities in chromosome number (non-disjunction) and to determine sex chromosomes
Parent cell
diploid somatic cell about to enter cell division
Daughter cell
a cell that is the product of cell division. In mitosis, daughter cells are identical o the mother cell; in meiosis, they are not identical to the parent cell
DNA
the genetic material found contained in the nucleus in eukaryotes (also in mitochondria and chloroplasts) and loose int he cytoplasm in prokaryotes, such as bacteria
Histones
proteins found in chromosomes that provide scaffolding for DNA to twine around so that the DNA can fit within the confined space of the nucleus
Chromatin
long fibres containing DNA, small amounts of RNA, and proteins. These fibres form chromosomes when they coil around histones
Centromere
a ‘button’ that holds the two identical sister chromatids together after the S phase of interphase and through mitosis until anaphase
Binary fission
cell division in prokaryotes (bacteria); simple because there is only one circular chromosome so no spindle is needed
Asexual reproduction
creation of a new organism without the input of cells form two separate organisms of opposite sexes; examples are binary fission, yeast and hydra budding, and vegetative propagation of plants
Cutting
type of vegetative propagation when a stem of a plant is cut off and produces roots, stems, leaves, and flowers; an asexual from of reproduction
Variation
the existence of many combinations of genes/traits in a population; improve the probability that some members will survive if environmental conditions change; is high in sexual reproduction
Mutation
a permanent change in a cell’s genetic structure, often resulting i the expression of a new trait or feature in the affected organism; usually due to random errors occurring during DNA replication or protein synthesis, but can also be cause by chemical or physical mutagens
Resistance
occurs when a drug removes susceptible bacteria or viruses from a population and leaves those variants (mutants) that are resistant to the drug. Rapid cell division ensures that the whole population becomes resistant quickly
Super bugs
bacteria that are immune to many antibiotics. Super bugs develop because of an overuse of antibiotics and antibacterial that have destroyed susceptible bacteria, leaving only those bacteria that are resistant to these drugs
Gametes
sex cells (sperm and egg); have half the normal chromosome umber so they can participate in fertilization
Fertilization
the fusion of an egg and sperm (gametes) to produce a zygote; occurs in sexual reproduction only
Sexual reproduction
the creation of offspring through the input of genetic material from two different organisms of opposite sexes (sperm from the male and egg from the female); increases variation
Gene
the unit of hereditary information that can be passed on to offspring; includes the specific DNA sequence encoding or regulating the sequence of a protein, tRNA, or rRNA molecule; determines the expression of a trait
